Having just had a couple of set backs in the family, I was reminded (again) about the importance of keeping a thorough food diary while doing a gut healing diet like GAPS.
A diary allows you to track exactly what you have been eating and doing each day and helps to make identifying what might have caused a problem easier. Now don't be misled, it is very often not clear what has caused a set back. Sometimes you have to just keep pressing on and it's only when you look back a few months later that you see a pattern emerging (unless it's really obvious). In order for the diary to be of any use, though it must be detailed. So here I will run down what to include and why.
Do list what activities you have done each day. May be you have had a period of being more busy than you realised.
Do list the quality of sleep you had each night, as poor sleep can quickly leave you feeling out of sorts and can impact how you feel.
Do list the supplements you are taking. Always keep these to the minimum as the binders and fillers can sometimes cause more problems than the issue you were taking them for. Try and stick to good food as much as you can.
Do make note of any untoward symptoms - e.g. headaches, stomach/digestive troubles/ pain/reoccurrence of symptoms that had gone/extra tiredness.
Do list not only the meals, but each individual ingredient in them. This may seem laborious, but it is essential. You may be reacting to a tiny little thing you decided to throw into the meal, like mustard powder, or a herb, or a particular vegetable and if it is not listed you will never remember it was added in if you just write 'chicken casserole'.
Do list your stool quality each day. This is big indicator of how well your body is utilising the food you feed into it. Check the Bristol Stool chart for an indication of what you should be aiming for.
I started out with just a notebook, but I was tempted to record skimpily. I now have a proper diary with a page to a day so I can have plenty of room to record the necessary details for all four of us.
When you hit a problem then first and foremost, DON'T PANIC. There is an excellent article on the subject here, but basically check for an obvious connection, like eating a new food for up to three days before. Remember that foods can affect you for up to three days after eating them. Consider STRESS as it plays a bigger part in our health than many of us like to acknowledge. If the issue continues, then start to look back. Is there any link between what you were eating/doing this time the symptoms previous time/s it has happened (if it has!). This can take quite a bit of detective work, but persevere. Keep going back to the diary check. you might have to keep mulling it over for a few days. See if the symptoms go and monitor the situation.
(I don't like the language on the SCD site referenced above, but it seems to be the only one that deals with such an important subject well.)
If you know you have been eating certain foods without symptoms then you can consider them to be safe. Keep a list of foods you know that you don't react to. If you need to, then cut anything not on the list out of your diet for a few days to return to a better state and then introduce ingredients you are not sure about slowly and only one every three days watching for reactions. I this way you can build your safe list and that will reduce the number of things you can suspect of causing problems.
Once you have a safe list, you could reduce to just listing new things, but I have to say that experience has shown me that once I relax my guard I miss things.
Personally, in our family the things that have caused problems have been cider vinegar, cheese (we introduced it too soon), too much fruit, especially strawberries and too much chocolate (now there's a surprise!) The chocolate caused terrible cramping and urgent trips to the bathroom at midnight several times before we finally identified the problem. After all, we reasoned, chocolate is safe, we've been having it for ages. Out came the food diary - only to find that on each occasion this strange manifestation occurred it had been an unusual day and we had consumed more chocolate than usual.
It sure is a relief when you get to the bottom of an issue, but it is a learning curve and we can now move on having made progress as we have identified the problem. It is easy to get stressed just trying to figure it out, but try and hang on in there and stay relaxed. Eventually it will become obvious. Just go back to those safe foods and DON'T PANIC - Oh and keep a thorough diary!
I'm off to keep mine up to date as I've already fallen foul of my own good advice. Hence I've found out the hard way the need to be detailed!
Disclaimer: I am not a doctor. A member of the medical profession should be consulted about all matters relating to your health. This information is for advice only.